The quality of an optical system depends largely upon the field of view, the correctness of the colors, and the clarity and intensity of the images presented to a viewer. Optical technicians are continually striving to improve these factors to provide the most realistic image possible within physical and economical constraints. The present invention is directed toward extending the field of view presented to a viewer into the peripheral viewing areas while maintaining current standards for image clarity, color, and intensity. The invention is further directed toward an apparatus that provides three-dimensional viewing, i.e., stereoscopic viewing, to a viewer.
Three-dimensional viewing systems are rapidly developing, due to the vast areas in which such technology is useful. Three-dimensional viewing systems duplicate normal visual perception and have applications in the areas of: undersea (submersible) maintenance and search equipment; robotics; high-security surveillance; hazardous materials handling; entertainment; training simulator technologies; and education, to name a few. The goal of such systems is to substitute a computer-generated, recorded, or real-time remote reality for the user's current reality. Such systems may include audio, visual, and motion inputs to the user in order to create a more realistic experience. The video aspect of such systems is known as stereoscopic viewing. Stereoscopy provides two views, i.e., a left and a right view, that are integrated by the viewer to give the impression of viewing three-dimensional objects.
A stereoscopic viewing system that presents images to a viewer's full field of view is desirable because these images will be more realistic, and thus will more closely resemble the actual environment being viewed. The field of view of a human eye is defined with respect to the head being stationary and the eye free to rotate about its socket. Generally, the eye perceives a relatively small object area with maximum visual acuity. More specifically, the macula latea, and within the macula latea, the fovea centralis region of the retina provides the sharpest and most detailed information of an object. Thus, the eyeball is continuously moving so that light coming from an object of primary interest falls upon the fovea centralis region of the retina. In terms of the field of view of an eye, the cone-shaped area to which an eye can scan and perceive with maximum visual acuity, i.e., light from this area falls on the macula/fovea region of the retina during the eye scan, is defined as the area of visual attention of the eye. The area falling outside the area of visual attention, but still perceptible by the eye as it scans the area of visual attention, is defined as the area of peripheral vision. The field of view of the eye is thus the area of visual attention coupled with the area of peripheral vision, with the head stationary and the eye utilizing normal eye scan.
The actual size of the area comprising a full field of view for a person depends, in part, upon the facial and other physical characteristics of the individual. For an average adult the area of visual attention for one eye is on the order of 120.degree. horizontal by 120.degree. vertical. It will be appreciated that the area of visual attention may be more appropriately regarded as cone-shaped with the 120.degree. by 120.degree. description being an approximation thereof. The left and right eyes perceive approximately the same objects in this 120.degree. by 120.degree. field of view, albeit from a slightly different perspective. The left and right areas of peripheral vision provide on the order of 60.degree. horizontal by 120.degree. vertical perception on the left and right sides of the area of visual attention, respectively, as the eyes scan the areas of visual attention. It is noted that the nose blocks the right eye from perceiving objects that fall into the left area of peripheral vision, and the left eye from perceiving objects that fall into the right area of peripheral vision.
The horizontal portions of the full field of view for an average adult right eye 16 are illustrated in FIG. 1. The angle .beta. depicts the area that is perceived with visual acuity as the eye scans the area of visual attention. The eye 16 is shown positioned at the leftmost and rightmost boundaries of its scan. Light reflected by objects within the cone-shaped region bounded by the angle .theta. would fall upon the macula/fovea region of the retina during the scan. The area of peripheral vision for the eye is depicted by the angle .beta., in the far right portion of FIG. 1, encompassing the area that the eye can perceive, but that does not fall within the area of visual attention. As is stated above, for the average adult eye the angles .theta. and .beta. are on the order of 120.degree. and 60.degree., respectively. An illustration of the field of view for the left eye would be similar to FIG. 1, with the nose 17 and peripheral area (angle .beta.) transposed. The full field of view for an average adult can thus be approximated as 120.degree. vertical by 240.degree. horizontal, the horizontal portion being equal to the area encompassing a 120.degree. field of visual attention (essentially the same objects perceived by each eye) and two 60.degree. fields of peripheral vision (each perceived by one eye only).
Optical systems have historically disregarded the peripheral fields of vision. Attempts to present a portion of the areas of peripheral vision have generally been expensive, room-size systems. Other efforts have focused on compressing a wide image into a small field of view. This compression of images by useful to the viewer in that the viewer can perceive a greater amount of information than with those systems that have a one-to-one correspondence between objects and images. However, the image generally suffers from distortion and other distracting characteristics. For example, FIG. 2 depicts an optical system 18 positioned in front of an eye 19. The optical system 18 compresses what is in reality 130.degree. of horizontal view (Image Plane) onto a viewing system that presents a field of view on the order of 100.degree. (angle .alpha.) to the viewer. This type of viewing system generally does not display images to the peripheral area (generally designated at 20), but this area is still perceived by the eye. The lack of visual information in the peripheral field of view is both distracting and annoying to a viewer, and takes away from the concept of a total visual reality environment.